Method for improving hard bias properties of layers in a magnetoresistive sensor

ABSTRACT

A method for improving hard bias properties of layers of a magnetoresistance sensor is disclosed. Properties of the hard bias layer are improved using a seedlayer structure that includes at least a first layer of silicon and a second layer comprising chromium or chromium molybdenum. Further, benefits are achieved when the seedlayer structure includes a layer of tantalum.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to magnetic storage systems, and moreparticularly to a method for improving hard bias properties of layers ofa magnetoresistance sensor.

2. Description of Related Art

Magnetic recording is a key and invaluable segment of theinformation-processing industry. While the basic principles are onehundred years old for early tape devices, and over forty years old formagnetic hard disk drives, an influx of technical innovations continuesto extend the storage capacity and performance of magnetic recordingproducts. For hard disk drives, the areal density on the magnetic mediumhas increased by a factor of millions since the first disk drive wasapplied to data storage. Such increases are based on correspondingimprovements in heads, media, drive electronics, and mechanics.

Magnetic recording heads have been considered the most significantfactor in areal-density growth. The ability of the magnetic recordingheads to both write and subsequently read magnetically recorded datafrom the medium at data densities well into the gigabits per square inch(Gbits/in²) range gives hard disk drives the power to remain thedominant storage device for many years to come.

Important components of computing platforms are mass storage devicesincluding magnetic disk and magnetic tape drives, where magnetic tapedrives are popular, for example, in data backup applications. Themagnetic disk drive includes a rotating magnetic disk, write and readheads that are suspended by a suspension arm above the rotating magneticdisk and an actuator that swings the suspension arm to place the readand write heads over selected circular tracks on the rotating disk.

Read and write heads are directly mounted on a slider that has anAir-Bearing Surface (ABS) between the slider and the rotating disk. Thesuspension arm biases the slider into contact with the surface of themagnetic disk when the magnetic disk is not rotating. However, when themagnetic disk rotates, air is swirled by the rotating disk adjacent tothe ABS causing the slider to ride on a cushion of air just above thesurface of the rotating magnetic disk.

The write and read heads are employed for writing magnetic data to andreading magnetic data from the rotating disk. The read and write headsare connected to processing circuitry that operates according to acomputer program to implement the writing and reading functions.

A magnetoresistive (MR) sensor detects magnetic field signals throughthe resistance changes of a sensing element as a function of thestrength and direction of magnetic flux being sensed by the sensingelement. Conventional MR sensors, such as those used as MR read headsfor reading data in magnetic recording disk and tape drives, operate onthe basis of the anisotropic magnetoresistive (AMR) effect of the bulkmagnetic material, which is typically permalloy. A component of the readelement resistance varies as the square of the cosine of the anglebetween the magnetization direction in the read element and thedirection of sense current through the read element. Recorded data canbe read from a magnetic medium, such as the magnetic disk in a magneticdisk drive, because the external magnetic field from the recordedmagnetic medium (the signal field) causes a change in the direction ofmagnetization in the read element, which in turn causes a change inresistance of the read element. This change in resistance may be used todetect magnetic transitions recorded on the recording media.

In the past several years, prospects of increased storage capacity havebeen made possible by the discovery and development of sensors based onthe giant magnetoresistance (GMR) effect, also known as the spin-valveeffect. In a spin valve sensor, the GMR effect varies as the cosine ofthe angle between the magnetization of the pinned layer and themagnetization of the free layer. Recorded data can be read from amagnetic medium because the external magnetic field from the recordedmagnetic medium, or signal field, causes a change in the direction ofmagnetization of the free layer, which in turn causes a change in theresistance of the spin valve sensor and a corresponding change in thesensed current or voltage.

Magnetic sensors utilizing the GMR effect are found in mass storagedevices such as, for example, magnetic disk and tape drives and arefrequently referred to as spin-valve sensors. The spin-valve sensors aredivided into two main categories, the Anti-FerroMagnetically (AFM)pinned spin valve and the self-pinned spin valve. A spin valve includesa pinned layer, a spacer and a free layer. The magnetization of the freelayer is free to rotate in response to the presence of external magneticfields. In an AFM pinned spin valve, the pinned layer has its magneticmoment pinned by a pinning layer. In the self-pinned spin valve, themagnetic moment of the pinned layer is pinned in the fabricationprocess.

The magnetic moment of the pinned layer may be pinned viamagnetostriction phenomenon and stress anisotropy. Magnetostriction isthe phenomenon in which a magnetic material changes its size dependingon its state of magnetization. External mechanical stress may alsocontribute to the state of the magnetic moment. For example, a positivemagnetostriction and compressive stress may be used to pin the pinnedlayer with the desired magnetic moment orientation. The self-pinnedlayer may be formed of a single layer of a single material or may be acomposite layer structure of multiple materials. It is noteworthy that aself-pinned spin valve requires no additional external layers formedadjacent to the pinned layer to maintain a desired magnetic orientationof the pinned layer and, therefore, is considered to be an improvementover the anti-ferromagnetically pinned spin valve.

In the construction of a sensor using the GMR effect, a hard magneticbias structure may be used to suppress the domain walls movement of thefree layer to provide a noise-free reproducing waveform. This isaccomplished by depositing hard magnetic thin films on both sides of thespin valve layers. A seedlayer structure is typically used to promotethe texture of the hard bias films. Chromium is often used as a hardbias seedlayer whereupon the hard bias layers are grown. However,properties of the hard bias layers degrade significantly when depositedon spin valve layers. In order to make better junctions, partiallymilled sensor structures down to platinum manganese (PtMn) or other spinvalve layers have been considered. The properties of the hard biaslayer, however, are degraded significantly on PtMn or on other spinvalve layers when deposited using the standard chromium (Cr) seedlayer.

It can be seen therefore, that there is a need for a method forimproving hard bias properties of layers of a magnetoresistance sensor.

SUMMARY OF THE INVENTION

To overcome the limitations in the prior art described above, and toovercome other limitations that will become apparent upon reading andunderstanding the present specification, the present invention disclosesa method for improving hard bias properties of layers of amagnetoresistance sensor.

The present invention improves the properties of a hard bias layer usinga seedlayer structure that includes at least a first layer of siliconand a second layer comprising chromium or chromium molybdenum. Further,benefits are achieved when the seedlayer structure includes a layer oftantalum.

A method for forming of forming a spin valve sensor according to anembodiment of the present invention includes forming a ferromagneticfree layer structure that has a magnetic moment, forming a ferromagneticpinned layer structure having a magnetic moment, forming a nonmagneticconductive spacer layer between the free layer structure and the pinnedlayer structure, forming an anti-ferromagnetic pinning layer coupled tothe pinned layer structure for pinning the magnetic moment of the pinnedlayer structure, forming hard magnetic thin films on both sides of atleast a portion of the free layer structure, the ferromagnetic pinnedlayer structure, the nonmagnetic conductive spacer layer and theanti-ferromagnetic pinning layer and forming a hard bias seedlayerstructure adjacent to at least a portion of the free layer structure,the ferromagnetic pinned layer structure, the nonmagnetic conductivespacer layer and the anti-ferromagnetic pinning layer, wherein theforming the hard bias seedlayer structure comprises forming at least afirst layer comprising silicon and a second layer comprising chromium orchromium molybdenum.

In another embodiment of the present invention, another method forforming a spin valve is provided. This method includes forming a spinvalve structure including a ferromagnetic free layer, a ferromagneticpinned layer and an anti- ferromagnetic pinning layer, forming hardmagnetic thin films adjacent at least a portion of the spin valvestructure on both sides of the spin valve structure and forming a hardbias seedlayer structure adjacent at least a portion of the spin valvestructure, wherein the forming the hard bias seedlayer structurecomprises forming at least a first layer comprising silicon and a secondlayer comprising chromium or chromium molybdenum.

In another embodiment of the present invention, a method for forming aseedlayer is provided. This method includes forming a first layercomprising silicon and forming a second layer comprising chromium orchromium molybdenum.

These and various other advantages and features of novelty whichcharacterize the invention are pointed out with particularity to theclaims annexed hereto and form a part hereof. However, for a betterunderstanding of the invention, its advantages, and the objects obtainedby its use, reference should be made to the drawings which form afurther part hereof, and to accompanying descriptive matter, in whichthere are illustrated and described specific examples of an apparatus inaccordance with the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers representcorresponding parts throughout:

FIG. 1 illustrates a storage system according to an embodiment of thepresent invention;

FIG. 2 illustrates one storage system according to an embodiment of thepresent invention;

FIG. 3 illustrates a slider mounted on a suspension according to anembodiment of the present invention;

FIG. 4 illustrates an ABS view of the slider and the magnetic headaccording to an embodiment of the present invention;

FIG. 5 illustrates an air bearing surface view of a GMR sensor accordingto an embodiment of the present invention;

FIG. 6 is a flow chart for providing a seedlayer structure according toembodiments of the present invention that provides significantimprovement in the properties of the hard bias layer when deposited onPtMn; and

FIG. 7 is a table showing the hard bias seedlayer structures and hardbias properties on PtMn coated substrates according to embodiments ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description of the exemplary embodiment, reference ismade to the accompanying drawings, which form a part hereof, and inwhich is shown by way of illustration the specific embodiments in whichthe invention may be practiced. It is to be understood that otherembodiments may be utilized as structural changes may be made withoutdeparting from the scope of the present invention.

The present invention provides a method for improving hard biasproperties of layers of a magnetoresistance sensor. Properties of thehard bias layer are improved using a seedlayer structure that includesat least a first layer of silicon and a second layer comprising chromiumor chromium molybdenum. Further, benefits are achieved when theseedlayer structure includes a layer of tantalum.

FIG. 1 illustrates an exemplary storage system 100 according to thepresent invention. A transducer 110 is under control of an actuator 120,whereby the actuator 120 controls the position of the transducer 110.The transducer 110 writes and reads data on magnetic media 130. Theread/write signals are passed to a data channel 140. A signal processor150 controls the actuator 120 and processes the signals of the datachannel 140 for data exchange with external Input/Output (I/O) 170. I/O170 may provide, for example, data and control conduits for a desktopcomputing application, which utilizes storage system 100. In addition, amedia translator 160 is controlled by the signal processor 150 to causethe magnetic media 130 to move relative to the transducer 110. Thepresent invention is not meant to be limited to a particular type ofstorage system 100 or to the type of media 130 used in the storagesystem 100.

FIG. 2 illustrates one particular embodiment of a multiple magnetic diskstorage system 200 according to the present invention. In FIG. 2, a harddisk drive storage system 200 is shown. The system 200 includes aspindle 210 that supports and rotates multiple magnetic disks 220. Thespindle 210 is rotated by motor 280 that is controlled by motorcontroller 230. A combined read and write magnetic head 270 is mountedon slider 260 that is supported by suspension 250 and actuator arm 240.Processing circuitry exchanges signals that represent information withread/write magnetic head 270, provides motor drive signals for rotatingthe magnetic disks 220, and provides control signals for moving theslider 260 to various tracks. Although a multiple magnetic disk storagesystem is illustrated, a single magnetic disk storage system is equallyviable in accordance with the present invention.

The suspension 250 and actuator arm 240 position the slider 260 so thatread/write magnetic head 270 is in a transducing relationship with asurface of magnetic disk 220. When the magnetic disk 220 is rotated bymotor 280, the slider 240 is supported on a thin cushion of air (airbearing) between the surface of disk 220 and the ABS 290. Read/writemagnetic head 270 may then be employed for writing information tomultiple circular tracks on the surface of magnetic disk 220, as well asfor reading information therefrom.

FIG. 3 is a diagram 300 that illustrates a slider 320 mounted on asuspension 322. First and second solder connections 302 and 308 connectleads from the sensor 318 to leads 310 and 314, respectively, onsuspension 322 and third and fourth solder connections 304 and 306connect to the write coil (not shown) to leads 312 and 316,respectively, on suspension 322.

FIG. 4 is an ABS view of slider 400 and magnetic head 410. The sliderhas a center rail 420 that supports the magnetic head 410, and siderails 430 and 460. The support rails 420, 430 and 460 extend from across rail 440. With respect to rotation of a magnetic disk, the crossrail 440 is at a leading edge 450 of slider 400 and the magnetic head410 is at a trailing edge 470 of slider 400.

The above description of a typical magnetic recording disk drive system,shown in the accompanying FIGS. 1–4, is for presentation purposes only.Storage systems may contain a large number of recording media andactuators, and each actuator may support a number of sliders. Inaddition, instead of an air-bearing slider, the head carrier may be onethat maintains the head in contact or near contact with the disk, suchas in liquid bearing and other contact and near-contact recording diskdrives.

FIG. 5 illustrates an air bearing surface view of a GMR sensor 500according to an embodiment of the present invention. GMR heads are veryattractive for use as high density recording magneto resistive (MR)heads because of their high readback output voltages, linear response,and symmetrical read sensitivity profiles.

In FIG. 5, an air bearing surface view of a GMR sensor 500 including endregions 512 and 514 separated by a central region 516 is shown. A freelayer (free ferromagnetic layer) 518 is separated from a pinned layer(AP-pinned ferromagnetic layer) 520 by a non-magnetic,electrically-conducting spacer layer 522 (typically, primarily copper).The magnetization of the pinned layer 520 may be fixed through exchangecoupling with an antiferromagnetic (AFM) layer 524. The magnetization ofthe free layer 518, however, is free to rotate in the presence of anexternal field. Free layer 518, spacer layer 522, pinned layer 520 andthe AFM layer 524 are all formed in the central region 516.

Hard bias layers 526 and 528 formed in the end regions 512 and 514,respectively, provide longitudinal bias for the free layer 518. Aseedlayer structure 550 is provided to promote the texture and enhancethe grain growth of each of the spin valve stack layers. Leads 530 and532 formed over hard bias layers 526 and 528, respectively, provideelectrical connections for the flow of the sensing current I_(s), from acurrent source 534 to the GMR sensor 500. A signal detector 540, whichis electrically connected to the leads 530 and 532, senses the change inresistance of the GMR sensor 500 due to changes induced by the externalmagnetic field (e.g., the field generated when a field transition on adisk is moved past the GMR sensor 500). A cap (not shown) is optionallyprovided on the free layer 518.

During the manufacturing of a read/write head for magnetic recordingmedia, the write head may be formed adjacent to the GMR sensor 500. Oneskilled in the art will realize that during the manufacture of the writehead, and during some of the processes involved in manufacturing the GMRsensor 500, itself, high temperature processes have inevitably beeninvolved. (Examples are the photoresist baking of the write head, theannealing of the AFM layer 524 materials on a substrate 510, which isrequired for some materials, and resetting of the pinned layer 520). Atthese temperatures, the grain boundaries of adjacent materials tend tobecome aligned, notably at the junction of the spacer 522 and the freelayer 518 and/or at the boundary of the spacer 522 and the pinned layer520. In this condition, it is very easy for diffusion between suchlayers to occur. This results in a degradation of the output signalamplitude produced by the GMR sensor 500.

Other constructions of the GMR sensor 500 are possible, and one skilledin the art could readily adapt the present invention for use with suchalternative constructions. For example, where pinned layers 520 havingmultiple layers are used, multiple iterations of the spacer 522 (anddiffusion barrier) could also be employed.

Within the sandwich structure of the GMR head sensor, i.e., “sensingfree layer”, “conducting space layer”, and “pinned layer”, themagnetization of the free layer 518 is free to respond to externalmagnetic field from the media. The magnetization of the pinned layer 520is pinned at about 90° to the magnetization of the free layer 518. Asthe conduction electrons are scattered between the free 518 and pinned520 layers through the spacer 522, the electrical resistance of the headchanges in response to the angle of the directions of magnetizationbetween the free 518 and pinned 520 layers.

In order to obtain a noise-free reproducing waveform, a hard magneticbias structure 526, 528 is required to suppress the domain wallsmovement of the free layer. This is accomplished by depositing hardmagnetic thin films 526, 528 in adjacent to the spin valve structure518–524 on both sides. The hard magnetic thin films 526, 528 supplylongitudinal magnetic flux to saturate the free layer 518 along its easyaxis to a single domain state. A seedlayer structure 550 is typicallyused to promote the texture and enhance the grain growth of each of thelayers 520, 522, 524, 516.

For hard magnetic thin films 526, 528 to be used in a GMR head, threefundamental magnetic properties are required in order to preventBarkhausen noise (due to domain movement, as mentioned above). First, toensure that a stable reproducing characteristic is maintained even whenan external magnetic field is applied, the hard magnetic bias layers526, 528 must have large coercive force (H_(c)). Second, the in-planeremnant magnetization (M_(r)) or M_(r) times thickness M_(t)) should belarge enough, since this is the component of the hard magnetic biaslayers 526, 528 that provides the longitudinal bias flux.

If the M_(r) of the hard magnetic bias layers 526, 528 is less than theM_(r) of the free layer 518, with the shared abutting junction,longitudinal bias for the free layer 518 is bound to fall short ofsupplying the necessary flux. This implies that the squareness(M_(r)/M_(s)) of the hysteresis loop of the hard bias layer along thein-plane direction should be high. Further, in order to provide thebiasing field and prevent noise a hard bias layers 526, 528 having ahigh coercivity is needed.

Properties of the hard bias layers 526, 528 degrade significantly whendeposited on spin valve layers. In order to make high areal densityheads, partially milled sensor structures have been considered. Theproperties of the hard bias layers 526, 528, however, are degradedsignificantly on PtMn or on other spin valve layers when deposited usingthe standard chromium (Cr) seedlayer structure. Therefore, theproperties of the hard bias layers 526, 528 are improved using a hardbias seedlayer structure 570 that includes at least a layer of chromiumor chromium molybdenum 572 and a layer 574 of silicon. Further, benefitsare achieved when the hard bias seedlayer structure 570 includes a layerof tantalum 576. Those skilled in the art will recognize that thepresent invention is not meant to be limited to thicknesses implied inFIG. 5.

FIG. 6 is a flow chart 600 for providing a seedlayer structure accordingto embodiments of the present invention that provides significantimprovement in the properties of the hard bias layer when deposited onPtMn or on other spin valve layers. In FIG. 6, a spin valve seedlayer isformed 610. An anti-ferromagnetic pinning layer is formed over the spinvalve seedlayer 612. A ferromagnetic pinned layer structure that has amagnetic moment is formed 620. A nonmagnetic conductive spacer layer isformed over the pinned layer structure 630. A ferromagnetic free layeris formed over the spacer layer 640. A photomask is formed over the spinvalve structure to mask the spin valve structure during ion milling 641.At least one of the free layer, spacer layer, pinned layer andanti-ferromagnetic layer is ion milled 642. A hard bias seedlayerstructure is formed, wherein the hard bias seedlayer structure comprisesat least a first layer of silicon and a second layer comprising chromiumor chromium molybdenum 644. The silicon layer may be formed on a layerof tantalum to form a trilayer seedlayer structure. Hard magnetic thinfilms are formed in an abutting relationship with the free layerstructure on both sides of the free layer structure 650.

Referring again to FIG. 5, the hard bias seedlayer structure 570according to embodiments of the present invention allows partially ionmilling the sensor down to the PtMn 524 or other spin valve layers anddepositing the hard bias layer 526, 528 to form the junctions. Thedeposition of the hard bias 526, 528 on PtMn or on other spin valvelayers eliminates the thick seedlayer structure requirement for pinnedspin valve structures. The hard bias seedlayer structure 570 accordingto embodiments of the present invention provides significant benefits toform ultra contiguous junctions (i.e., junctions having sharp edges)because it will dramatically reduce the amount of the sidewalldeposition. Furthermore, this will significantly reduce the complexityof the ion milling process for pinned spin valve structures. Therefore,the hard bias seedlayer structure 570 includes at least a layer ofsilicon 572 and a layer 574 comprising chromium or chromium molybdenum.Further, as described above, the silicon layer may be formed on a layerof tantalum 576 to form a trilayer seedlayer structure.

FIG. 7 illustrates a table 700 that shows the hard bias coercivity andthe squareness with various seedlayer structure combinations. As seen,the Ta/Si/CrMo seems to provide better H_(c) and squareness, while allother seedlayers improve the H_(c) of the hard bias. For example, withstandard chromium seedlayer structures, the coercivity and squareness ofthe hard bias on PtMn coated substrate or on other spin valve layers areapproximately 500 Oe and 0.8 respectively.

Referring to FIG. 7, the first structure 710 includes a seedlayerstructure of silicon 712 and chromium 714. The coercivity 770 isincreased but the effect on the squareness 771 is less significant. Thesecond structure 716 also includes a seedlayer structure of silicon 718and chromium 720, but with the thickness of the silicon layer 718increased. When compared to the first structure 710, the coercivity 772is reduced some, but the squareness 773 increases, albeit slightly.

The third structure 722 includes a seedlayer structure of tantalum 724,silicon 726 and chromium 728. When compared to the first structure 710,the coercivity 774 is reduced some, although not as much as in thesecond structure 716, and the squareness 775 increases significantly.The fourth first structure 730 includes a seedlayer structure oftantalum 732, silicon 734 and chromium 736, with the thickness of thetantalum 732 increased over thickness of the tantalum 724 of the thirdstructure 722. This, reduces both the coercivity 776 and squareness 777.

The fifth structure 738 includes a seedlayer structure of chromium 740,silicon 742 and chromium 744. The coercivity 778 is greater than 1300Oe, but the squareness 779 is still less than 0.9. The same is true forthe sixth structure 746, which includes a seedlayer structure ofchromium 748, silicon 750 and chromium 752, wherein the thickness of thechromium layer 748 is doubled over the chromium layer 740 of the fifthstructure 738. The coercivity 780 and the squareness 781 of the sixthstructure 746 are about the same as the coercivity 778 and squareness779 of the fifth structure 738.

The seventh 754 and eighth 762 structures show the greatest improvement.The seventh structure 754 includes a seedlayer structure of tantalum756, silicon 758 and chromium-molybendum 760. The coercivity 782 isincreased significantly as is the squareness 783. The eighth structure762 doubles the thickness of the tantalum layer 764, but still includessilicon 766 and chromium-molybendum 768. This increases the coercivity784 slightly, but decreases the squareness 785 slightly.

Accordingly, the properties of the hard bias layer are improved using aseedlayer structure that includes at least a first layer of silicon anda second layer comprising chromium or chromium molybdenum. Further,benefits are achieved when the seedlayer structure includes a layer oftantalum.

The foregoing description of the exemplary embodiment of the inventionhas been presented for the purposes of illustration and description. Itis not intended to be exhaustive or to limit the invention to theprecise form disclosed. Many modifications and variations are possiblein light of the above teaching. It is intended that the scope of theinvention be limited not with this detailed description, but rather bythe claims appended hereto.

1. A method of forming a spin valve sensor, comprising: forming aferromagnetic free layer structure that has a magnetic moment; forming aferromagnetic pinned layer structure having a magnetic moment; forming anonmagnetic conductive spacer layer between the free layer structure andthe pinned layer structure; forming an anti-ferromagnetic pinning layercoupled to the pinned layer structure for pinning the magnetic moment ofthe pinned layer structure; forming hard magnetic thin films on bothsides of at least a portion of the free layer structure, theferromagnetic pinned layer structure, the nonmagnetic conductive spacerlayer and the anti-ferromagnetic pinning layer; and forming a hard biasseedlayer structure adjacent to and on opposite sides of at least aportion of the free layer structure, the ferromagnetic pinned layerstructure, the nonmagnetic conductive spacer layer and theanti-ferromagnetic pinning layer, wherein the forming the hard biasseedlayer structure comprises forming at least a first layer comprisingsilicon and a second layer comprising chromium or chromium molybdenum.2. The method of claim 1, wherein the forming the anti-ferromagneticpinning layer further comprising forming a layer of platinum manganese.3. The method of claim 1, wherein the forming the hard bias seedlayerstructure further comprises forming a layer of tantalum adjacent thesilicon layer.
 4. The method of claim 3, wherein the forming a layer oftantalum adjacent the silicon layer further comprises forming thetantalum and silicon layer with equal thickness.
 5. The method of claim3, wherein the forming a layer of tantalum adjacent the silicon layerfurther comprises forming the tantalum layer with a thickness half athickness of the silicon layer.
 6. The method of claim 3, wherein theforming a layer of tantalum further comprises forming atantalum-chromium alloy layer.
 7. The method of claim 6, wherein theforming the tantalum-chromium alloy layer further comprises forming thetantalum-chromium alloy layer silicon layer with equal thickness.
 8. Themethod of claim 6, wherein the forming the tantalum-chromium alloy layerfurther comprises forming the tantalum-chromium alloy layer thicknesshalf a thickness of the silicon layer.
 9. The method of claim 1, whereinthe forming the hard bias seedlayer structure further comprises formingat opposite sides of at least a portion of the free layer structure, theferromagnetic pinned layer structure, the nonmagnetic conductive spacerlayer and the anti-ferromagnetic pinning layer, a first layer oftantalum, a second layer of silicon and a third layer comprisingchromium.
 10. The method of claim 1, wherein the forming the hard biasseedlayer structure further comprises forming at opposite sides of atleast a portion of the free layer structure, the ferromagnetic pinnedlayer structure, the nonmagnetic conductive spacer layer and theanti-ferromagnetic pinning layer, a first layer of tantalum, a secondlayer of silicon and a third layer comprising chromium-molybdenum. 11.The method of claim 10, wherein the pinning layer comprises platinummanganese.
 12. The method of claim 10, wherein the forming the hard biasseedlayer structure further comprises forming a layer of tantalumadjacent the silicon layer.
 13. The method of claim 12, wherein theforming a layer of tantalum adjacent the silicon layer further comprisesforming the tantalum and silicon layer with equal thickness.
 14. Themethod of claim 12, wherein the forming a layer of tantalum adjacent thesilicon layer further comprises forming the tantalum layer with athickness half a thickness of the silicon layer.
 15. The method of claim12, wherein the forming a layer of tantalum further comprises forming atantalum-chromium alloy layer.
 16. The method of claim 15, wherein theforming the tantalum chromium alloy layer further comprises forming thetantalum-chromium alloy layer and the silicon layer with equalthickness.
 17. The method of claim 15, wherein the forming thetantalum-chromium alloy layer further comprises forming thetantalum-chromium alloy lay thickness half a thickness of the siliconlayer.
 18. A method of forming a spin valve sensor, comprising: forminga spin valve structure including a ferromagnetic free layer, aferromagnetic pinned layer and an anti-ferromagnetic pinning layer;forming hard magnetic thin films adjacent at least a portion of the spinvalve structure on both sides of the spin valve structure; and forming ahard bias seedlayer structure adjacent to and on opposite sides of atleast a portion of the spin valve structure, wherein the forming thehard bias seedlayer structure comprises forming at least a first layercomprising silicon and a second layer comprising chromium or chromiummolybdenum.
 19. The method of claim 18, wherein the forming the hardbias seedlayer structure further comprises forming at opposite sides ofat least a portion of the free layer structure, the ferromagnetic pinnedlayer structure, the nonmagnetic conductive spacer layer and theanti-ferromagnetic pinning layer, a first layer of tantalum, a secondlayer of silicon and a third layer comprising chromium.
 20. The methodof claim 18, wherein the forming the hard bias seedlayer structurefurther comprises forming at opposite sides of at least a portion of thefree layer structure, the ferromagnetic pinned layer structure, thenonmagnetic conductive spacer layer and the anti-ferromagnetic pinninglayer, a first layer of tantalum, a second layer of silicon and a thirdlayer comprising chromium-molybdenum.
 21. A method of forming a hardbias seedlayer structure, comprising: forming a first layer comprisingsilicon adjacent to and on opposite sides of a spin valve structure; andforming a second layer comprising chromium or chromium molybdenumadjacent to the first layer.
 22. The method of claim 21 furthercomprising forming a layer of tantalum adjacent the silicon layer.